7 ms·

2×4 Lumber Sizes – The History Behind the Mystery

31 points by NoRagrets 3y ago

ssss11 3y ago
“The modern-day dimensions of a 2×4 are smaller due to historical practices and practical considerations. Thinner pieces of wood were favored over time to reduce shipping costs and increase efficiency in transportation. These dimensions eventually became standardized to strike a balance between cost-efficiency and structural integrity.” I guess keep an eye on whether they continue to get smaller over time.. the above is a nice explanation but it could just be shrinkflation.
- nick222226 3y ago
  They certainly seem to get closer to the minimum acceptable ANSI or lumber association standards as computerized mills optimize cuts further.
- dclowd9901 3y ago
  I always figured it was due to milling to finished dimensions from raw lumber. You can buy unmilled lumber by the board-foot (basically 1”x12”x12”), and you get exact pay for dimensions, but when you’re buying finished, milled lumber the only thing that you can trust is that it’s been milled to a standard. In other words, they start with ~2”x~4” and mill to exactly 1.5”x3.5” Don’t ask me why that all changes at 1/2” dimensions.
blendergeek 3y ago
Website seems to be suffering from hug of death. https://web.archive.org/web/20231212021652/https://workingforest.com/2x4-lumber-size-the-history-behind-the-mystery/ https://web.archive.org/web/20231212021652/https://workingfo...
porknubbins 3y ago
2x4s are one of the only things I can think of whose entire name is just literally raw dimensions, so finding out they are not even right was a real wtf moment.
- hotpotamus 3y ago
  If you’ve ever done construction work (particularly framing obviously) you tend to realize it very quickly, but you get quite used to dealing with it; it’s all quite standardized, simple carpentry. A lot of batteries like 18650’s or CR2032’s as examples are basically just their size in millimeters, and as far as I know, they are accurate.
- gonzo41 3y ago
  Just wait until you find out about the quarter pounder. :)
  - wsinks 3y ago
    Aren't those supposed to be a quarter pound before cooking?
  - DonHopkins 3y ago
    I ordered a quarter pounder at a McDonald's drive through, and the cashier said, "There will be a wait on that." I asked, "Oh really? How much will it weigh?" There was a long pause, and they finally said, "About 5 minutes."
    - XorNot 3y ago
      This is an A+ dad joke, you should be proud.
  - jszymborski 3y ago
    The precook weight used to be 4oz (1/4 lbs) but is now 4.25oz, which, I mean, all told, isn't all that different.
- dec0dedab0de 3y ago
  kind of like the footlong from subway
  - gruez 3y ago
codelorado 3y ago
This video does a better job to explain the underlying reasons: https://www.youtube.com/watch?v=WaJFudED5FQ https://www.youtube.com/watch?v=WaJFudED5FQ.
- iclelland 3y ago
  That video does exactly the same job explaining the underlying reasons -- down to using much of the same wording, and the same visuals. And it was online for a few weeks before this article was published.
  - iguessthislldo 3y ago
    One even has a watermark and a Youtube seek bar. This was painfully obvious.
rascul 3y ago
As long as the lumber is a standard size then it can be accounted for. The problem is that when dimensions get too far from what you need then you have to use more lumber and/or make a lot more scrap, leading to more cost in both material and labor. A lot of things in home building are based upon standard lumber dimensions. That said, even after building with dimensional lumber for decades, it's still weird to me that a 2x4 isn't 2x4.
- JHonaker 3y ago
  I'm just getting into woodworking. This has been a consistent source of confusion. It's no simpler with rough lumber. The usable yield of 4/4 (i.e. four quarter, or a one inch thick rough piece) is at least 13/16 of an inch after surfacing two sides.
hazmazlaz 3y ago
TL;DR - 2x4 is the rough dimensions, the pieces are planed (have surface material removed) to create a smoother/finished surface on the board and the final dimensions are slightly smaller than 2x4 as a result.
Kon-Peki 3y ago
> Wood manufacturers faced a significant challenge in the late 1800s when forests near major cities were depleted, necessitating the shipping of lumber over longer distances. However, the exorbitant costs of railroad shipping, often double the price of the lumber itself, prompted manufacturers to find innovative solutions. There was a book recommended here on HN a few months ago - Nature's Metropolis - that devotes an entire chapter to why and how, in the second half of the 1800s, shipping green lumber to Chicago lumber yards came to dominate the entire industry. Yet that changed very suddenly as the above quote points out. The TLDR is that within an hour or so of arriving in Chicago, your load of lumber would go to auction, be bought, and you'd have cold hard cash in your pocket. To facilitate this, the Chicago yards all agreed to adopt size and quality standards like the grain elevators had. Other cities paid much more, but took days or weeks and you got a promissory note rather than cash. But at some point the railroads started charging by weight rather than by carload, and it was worth drying your lumber before shipping. Nobody shipped to those Chicago yards after that, so someone else had to take over the standardization of dried lumber.
- cincinnatus 3y ago
  I live in a building built in the 40s near Chicago and I've done a lot of work that exposed various parts of the underlying structure, and the history you describe is all over the place. The dimensional lumber in the walls and floors/ceilings are widely varied and rough, not planed to anything too terribly specific. To add further injury built on sand because we're on a dune by the beach, Which as you can imagine means things are never square or plumb :-) I recently realized that the steel beams in the ceiling of the bar (building used to be a bar/restaurant/inn) are actually old railroad ties or something. Chicago industry baby! :-D
opwieurposiu 3y ago
The relevant standard is called PS20, American Softwood Lumber Standard: https://www.nist.gov/system/files/documents/2021/10/26/PS%2020-20%20Revsion%201%20October%202021.pdf https://www.nist.gov/system/files/documents/2021/10/26/PS%20... Note also that green wood will shrink as it dries, so the moisture content at the time of grading makes a difference.
anticensor 3y ago
If you want real ones, then request metric, 5x10 is always 5cmx10cm.

31 points by NoRagrets 3y ago

“The modern-day dimensions of a 2×4 are smaller due to historical practices and practical considerations. Thinner pieces of wood were favored over time to reduce shipping costs and increase efficiency in transportation. These dimensions eventually became standardized to strike a balance between cost-efficiency and structural integrity.” I guess keep an eye on whether they continue to get smaller over time.. the above is a nice explanation but it could just be shrinkflation.

nick222226 3y ago
They certainly seem to get closer to the minimum acceptable ANSI or lumber association standards as computerized mills optimize cuts further.
dclowd9901 3y ago
I always figured it was due to milling to finished dimensions from raw lumber. You can buy unmilled lumber by the board-foot (basically 1”x12”x12”), and you get exact pay for dimensions, but when you’re buying finished, milled lumber the only thing that you can trust is that it’s been milled to a standard. In other words, they start with ~2”x~4” and mill to exactly 1.5”x3.5” Don’t ask me why that all changes at 1/2” dimensions.

blendergeek 3y ago

Website seems to be suffering from hug of death. https://web.archive.org/web/20231212021652/https://workingforest.com/2x4-lumber-size-the-history-behind-the-mystery/ https://web.archive.org/web/20231212021652/https://workingfo...

porknubbins 3y ago

2x4s are one of the only things I can think of whose entire name is just literally raw dimensions, so finding out they are not even right was a real wtf moment.

hotpotamus 3y ago
If you’ve ever done construction work (particularly framing obviously) you tend to realize it very quickly, but you get quite used to dealing with it; it’s all quite standardized, simple carpentry. A lot of batteries like 18650’s or CR2032’s as examples are basically just their size in millimeters, and as far as I know, they are accurate.
gonzo41 3y ago
Just wait until you find out about the quarter pounder. :)
- wsinks 3y ago
  Aren't those supposed to be a quarter pound before cooking?
- DonHopkins 3y ago
  I ordered a quarter pounder at a McDonald's drive through, and the cashier said, "There will be a wait on that." I asked, "Oh really? How much will it weigh?" There was a long pause, and they finally said, "About 5 minutes."
  - XorNot 3y ago
    This is an A+ dad joke, you should be proud.
- jszymborski 3y ago
  The precook weight used to be 4oz (1/4 lbs) but is now 4.25oz, which, I mean, all told, isn't all that different.
dec0dedab0de 3y ago
kind of like the footlong from subway
- gruez 3y ago

codelorado 3y ago

This video does a better job to explain the underlying reasons: https://www.youtube.com/watch?v=WaJFudED5FQ https://www.youtube.com/watch?v=WaJFudED5FQ.

iclelland 3y ago
That video does exactly the same job explaining the underlying reasons -- down to using much of the same wording, and the same visuals. And it was online for a few weeks before this article was published.
- iguessthislldo 3y ago
  One even has a watermark and a Youtube seek bar. This was painfully obvious.

rascul 3y ago

As long as the lumber is a standard size then it can be accounted for. The problem is that when dimensions get too far from what you need then you have to use more lumber and/or make a lot more scrap, leading to more cost in both material and labor. A lot of things in home building are based upon standard lumber dimensions. That said, even after building with dimensional lumber for decades, it's still weird to me that a 2x4 isn't 2x4.

JHonaker 3y ago
I'm just getting into woodworking. This has been a consistent source of confusion. It's no simpler with rough lumber. The usable yield of 4/4 (i.e. four quarter, or a one inch thick rough piece) is at least 13/16 of an inch after surfacing two sides.

hazmazlaz 3y ago

TL;DR - 2x4 is the rough dimensions, the pieces are planed (have surface material removed) to create a smoother/finished surface on the board and the final dimensions are slightly smaller than 2x4 as a result.

Kon-Peki 3y ago

> Wood manufacturers faced a significant challenge in the late 1800s when forests near major cities were depleted, necessitating the shipping of lumber over longer distances. However, the exorbitant costs of railroad shipping, often double the price of the lumber itself, prompted manufacturers to find innovative solutions. There was a book recommended here on HN a few months ago - Nature's Metropolis - that devotes an entire chapter to why and how, in the second half of the 1800s, shipping green lumber to Chicago lumber yards came to dominate the entire industry. Yet that changed very suddenly as the above quote points out. The TLDR is that within an hour or so of arriving in Chicago, your load of lumber would go to auction, be bought, and you'd have cold hard cash in your pocket. To facilitate this, the Chicago yards all agreed to adopt size and quality standards like the grain elevators had. Other cities paid much more, but took days or weeks and you got a promissory note rather than cash. But at some point the railroads started charging by weight rather than by carload, and it was worth drying your lumber before shipping. Nobody shipped to those Chicago yards after that, so someone else had to take over the standardization of dried lumber.

cincinnatus 3y ago
I live in a building built in the 40s near Chicago and I've done a lot of work that exposed various parts of the underlying structure, and the history you describe is all over the place. The dimensional lumber in the walls and floors/ceilings are widely varied and rough, not planed to anything too terribly specific. To add further injury built on sand because we're on a dune by the beach, Which as you can imagine means things are never square or plumb :-) I recently realized that the steel beams in the ceiling of the bar (building used to be a bar/restaurant/inn) are actually old railroad ties or something. Chicago industry baby! :-D

opwieurposiu 3y ago

The relevant standard is called PS20, American Softwood Lumber Standard: https://www.nist.gov/system/files/documents/2021/10/26/PS%2020-20%20Revsion%201%20October%202021.pdf https://www.nist.gov/system/files/documents/2021/10/26/PS%20... Note also that green wood will shrink as it dries, so the moisture content at the time of grading makes a difference.

anticensor 3y ago

If you want real ones, then request metric, 5x10 is always 5cmx10cm.